/*
 * Compilation Copyright (c) 1995-2019 by Wei Dai.  All rights reserved.
 *	This copyright applies only to this software distribution package
 *	as a compilation, and does not imply a copyright on any particular
 *	file in the package.
 * 
 *	Boost Software License - Version 1.0 - August 17th, 2003
 *
 *	Permission is hereby granted, free of charge, to any person or organization
 *	obtaining a copy of the software and accompanying documentation covered by
 *	this license (the "Software") to use, reproduce, display, distribute,
 *	execute, and transmit the Software, and to prepare derivative works of the
 *	Software, and to permit third-parties to whom the Software is furnished to
 *	do so, all subject to the following:
 * 
 *	The copyright notices in the Software and this entire statement, including
 *	the above license grant, this restriction and the following disclaimer,
 *	must be included in all copies of the Software, in whole or in part, and
 *	all derivative works of the Software, unless such copies or derivative
 *	works are solely in the form of machine-executable object code generated by
 *	a source language processor.
 *
 *	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *	FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
 *	SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
 *	FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
 *	ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 *	DEALINGS IN THE SOFTWARE.
 */

// hmac.h - originally written and placed in the public domain by Wei Dai

/// \file hmac.h
/// \brief Classes for HMAC message authentication codes

#ifndef CRYPTOPP_HMAC_H
#define CRYPTOPP_HMAC_H

#include "seckey.h"
#include "secblock.h"

NAMESPACE_BEGIN(CryptoPP)

/// \brief HMAC information
/// \details HMAC_Base derives from VariableKeyLength and MessageAuthenticationCode
/// \since Crypto++ 2.1
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE HMAC_Base : public VariableKeyLength<16, 0, INT_MAX>, public MessageAuthenticationCode
{
public:
	virtual ~HMAC_Base() {}

	/// \brief Construct a HMAC_Base
	HMAC_Base() : m_innerHashKeyed(false) {}
	void UncheckedSetKey(const byte *userKey, unsigned int keylength, const NameValuePairs &params);

	void Restart();
	void Update(const byte *input, size_t length);
	void TruncatedFinal(byte *mac, size_t size);
	unsigned int OptimalBlockSize() const {return const_cast<HMAC_Base*>(this)->AccessHash().OptimalBlockSize();}
	unsigned int DigestSize() const {return const_cast<HMAC_Base*>(this)->AccessHash().DigestSize();}

protected:
	virtual HashTransformation & AccessHash() =0;
	byte * AccessIpad() {return m_buf;}
	byte * AccessOpad() {return m_buf + AccessHash().BlockSize();}
	byte * AccessInnerHash() {return m_buf + 2*AccessHash().BlockSize();}

private:
	void KeyInnerHash();

	SecByteBlock m_buf;
	bool m_innerHashKeyed;
};

/// \brief HMAC
/// \tparam T HashTransformation derived class
/// \details HMAC derives from MessageAuthenticationCodeImpl. It calculates the HMAC using
///   <tt>HMAC(K, text) = H(K XOR opad, H(K XOR ipad, text))</tt>.
/// \sa <a href="http://www.weidai.com/scan-mirror/mac.html#HMAC">HMAC</a>
/// \since Crypto++ 2.1
template <class T>
class HMAC : public MessageAuthenticationCodeImpl<HMAC_Base, HMAC<T> >
{
public:
	CRYPTOPP_CONSTANT(DIGESTSIZE=T::DIGESTSIZE)
	CRYPTOPP_CONSTANT(BLOCKSIZE=T::BLOCKSIZE)

	virtual ~HMAC() {}

	/// \brief Construct a HMAC
	HMAC() {}
	/// \brief Construct a HMAC
	/// \param key the HMAC key
	/// \param length the size of the HMAC key
	HMAC(const byte *key, size_t length=HMAC_Base::DEFAULT_KEYLENGTH)
		{this->SetKey(key, length);}

	static std::string StaticAlgorithmName() {return std::string("HMAC(") + T::StaticAlgorithmName() + ")";}
	std::string AlgorithmName() const {return std::string("HMAC(") + m_hash.AlgorithmName() + ")";}
	std::string AlgorithmProvider() const {return m_hash.AlgorithmProvider();}

private:
	HashTransformation & AccessHash() {return m_hash;}

	T m_hash;
};

NAMESPACE_END

#endif
